1. Technical Field
The subject matter described here generally relates to wind turbines, and, more particularly, to a frame support for a wind turbine.
2. Related Art
A wind turbine is a machine for converting the kinetic energy in wind into mechanical energy. If the mechanical energy is used directly by the machinery, such as to pump water or to grind wheat, then the wind turbine may be referred to as a windmill. Similarly, if the mechanical energy is converted to electricity, then the machine may also be referred to as a wind generator or wind power plant.
Wind turbines are typically categorized according to the vertical or horizontal axis about which the blades rotate. One so-called horizontal-axis wind generator is schematically illustrated in FIG. 1 and available from General Electric Company. This particular configuration for a wind turbine 2 includes a tower 4 supporting a nacelle 6 enclosing a drive train 8. The blades 10 are arranged on a hub to form a “rotor” at one end of the drive train 8 outside of the nacelle 6. The rotating blades 10 drive a gearbox 12 connected to an electrical generator 14 at the other end of the drive train 8 arranged inside the nacelle 6 along with a control system 16 that receives input from an anemometer 18.
Commonly-assigned U.S. Pat. No. 7,126,236 for “Methods and Apparatus for Pitch Control Power Conversion” is incorporated by reference here and partially reproduced in FIG. 2. In FIG. 2, the drive train 8 of the wind turbine 4 (shown in FIG. 1) includes a main rotor shaft 116 connected to hub 110 and the gear box 12. The control system 16 (FIG. 1) includes one or more microcontrollers within panel 112 which provide control signals to variable pitch blade drive 114. A high speed shaft (not shown in FIG. 2) is used to drive a first generator 120 via coupling 122. Various components are supported by a frame 132. The frame 132 typically includes a main frame or “bedplate” portion, and generator support frame or “rear frame” portion that is cantilevered from the bedplate. However, the frame 132 may, under certain conditions, be subject to high stresses that can cause fatigue cracking and/or failure, particularly at the joint between the bedplate and the generator support frame.